How to register and load an old downloaded image

NOTE: This applies only to old images. We now provide OVA appliances that can be imported directly through VirtualBox without hassles

Uncompress the file you have downloaded from us.
If it is a single file, you are set; if you got an archive (we used to provide XML templates for use with old versions of VirtualBox), take only the .vdi file.
Place the virtual disk image in it in a directory of your choice.

Create a new virtual machine: in “VM Name and OS Type”, choose one of “Linux”, “BSD” or “Other”, and then choose the profile that best fits your image in “Version” (for example, if you downloaded an Ubuntu virtual disk image, choose the “Linux” and “Ubuntu” pair). If you have downloaded a disk image of a Linux distribution whose name is not shown in the dropdown list, choose “Linux 2.6″ or “Linux 2.6 (64 bit)”, except when the notes on the download page specify otherwise. At the end, click on Next.

In “Memory”, leave everything as it is, unless you explicitly need more RAM assigned to your guest.

In “Virtual Hard Disk”, select “Use existing hard disk”, click on and use the dialog to select the virtual disk image file you uncompressed in the first step.

Click “Next” and then “Finish”. Your virtual machine should be ready for use.